In test of eleven products, a fogger and DEET worked, herbs and citronella didn’t.

Already daydreaming about warm, outdoor barbecues and picnics? If so, one thing you’re probably leaving out of your happy vision is the inevitable return of blood-thirsty mosquitoes that crash those otherwise relaxing outdoor events. Luckily, this year, researchers have your back, as Science first reported.

In a high-tech experiment to recreate your bite risks while chilling on your patio, researchers at New Mexico State University tested out 11 common types of mosquito repellent to find the most effective ones. The results: skip the citronella candles and ditch herb-laced bracelets—they didn’t work at keeping away mosquitoes. Instead, stick with DEET-containing products, metofluthrin-blowing clip-on fans, and sprays containing oil of lemon eucalyptus. The results appear in the Journal of Insect Science.

To test out the products, the researchers set up a three-chamber cage of mosquitoes in a wind tunnel, gently blowing at 2 meters/second. Here's how the experiment works: A pack of hungry Ae. aegypti mosquitoes (50 to 125) enters into the middle compartment and can fly to either side—upwind or down. Next, the researchers place some delicious human “bait” one meter upwind of the cage. (The researchers made sure that volunteers didn’t bathe in the 15 hours prior so that the mosquitoes could get a good whiff.) After a little time, the researchers seal off the chambers and tally up how the mosquitoes distribute—toward the bait or not.

In a positive control, 88.8 percent stalked the chamber closest to the bait. In a negative control with no bait, only 17 percent roamed the upwind chamber.

Next, the researchers tried out 11 different types of mosquito repellant on the bait. The products included bracelets, wearable devices, sprays, and citronella candles. The most effective products were, in order of rank:

The OFF! Clip-on, which is a wearable device that spews a fog of metofluthrin insecticide. Only 27 percent of mosquitoes were in the upwind chamber, about a 70 percent reduction in mosquito attraction.

Cutter Lemon Eucalyptus, a spray of oil of lemon eucalyptus. Only 29.6 percent of the mosquitoes were in the upwind chamber.

Ben’s Tick & Insect Repellent, a spray-on containing 98 percent DEET. Only 33.7 percent of mosquitoes were in the upwind chamber, a reduction of around 60 percent.

The authors are hopeful that the information can better inform consumers about how to best protect against bites. “At a time where vector-borne diseases like Zika are a real threat, the most egregious danger to the consumer is the false comfort that some repellents give them protection against Ae. aegypti when they actually offer none,” the authors conclude.

I spend a good amount of time in the backcountry, and can unscientifically verify this, with a caveat - I have noticed an apparent regional variation in which products work better.

Lemon Eucalyptus works much better than 100% DEET in Canada's Algonquin Provincial Park, but didn't seem to work at all in Everglades National Park; DEET was much more effective there. They seem to work the same in New York State and Colorado, however, the mosquito population in CO was so much lower overall, it's hard to say.

All that said, it's also important to note the longevity of the repellent. IME, DEET will last for hours, up to a day depending on weather. Lemon Eucalyptus will require some reapplications. I had high hopes for Parcardin, but its effectiveness seemed to wear off much quicker than other options.

1) Different species of mosquitoes have different scent preferences. You definitely see that when using attractants to trap them. It stands to reason they also get turned off by different scents differently.

2) Some repellents are intended primarily to stop mosquitoes from biting, and might be effective even if mosquitoes still approach. The more sensitive question (though less fun to test) is how many land on the bait and how many bite.

I spend a good amount of time in the backcountry, and can unscientifically verify this, with a caveat - I have noticed an apparent regional variation in which products work better.

Lemon Eucalyptus works much better than 100% DEET in Canada's Algonquin Provincial Park, but didn't seem to work at all in Everglades National Park; DEET was much more effective there. They seem to work the same in New York State and Colorado, however, the mosquito population in CO was so much lower overall, it's hard to say. Different species?

All that said, it's also important to note the longevity of the repellent. IME, DEET will last for hours, up to a day depending on weather. Lemon Eucalyptus will require some reapplications. I had high hopes for Parcardin, but its effectiveness seemed to wear off much quicker than other options.

If I recall correctly, the length of DEET effectiveness scales at about one hour per 10-15% DEET in the product.

I'm happy to see that the lemon eucalyptus product performed so well. For decades I've trusted only DEET-containing products, but on longer camping trips I've worried about what the health effects could be from daily use of DEET without access to running water to wash it all away. The fact that lemon eucalyptus outperformed DEET is both surprising and encouraging.

Plus, my pets will be happy to finally have mosquito repellent that they can wear too

My +1: those bracelets do something... they stink up your sleeves, or the entire contents of a backpack if you were unfortunate enough to forget they were left in there. They also have a mini-game built into them: they turn the entire trip into a game of holding your bracelet arm downwind from your nose.

I'm happy to see that the lemon eucalyptus product performed so well. For decades I've trusted only DEET-containing products, but on longer camping trips I've worried about what the health effects could be from daily use of DEET without access to running water to wash it all away. The fact that lemon eucalyptus outperformed DEET is both surprising and encouraging.

Plus, my pets will be happy to finally have mosquito repellent that they can wear too

Why would lemon eucalyptus be safer for you then DEET? Because one smells less like a chemical?

I'm pretty sure the CDC suggests DEET for young children but not lemon eucalyptus so your intuition on which is safer is probably way off.

That said I'm going to use lemon eucalyptus because it smells better, regardless of any health issues..

I'm happy to see that the lemon eucalyptus product performed so well. For decades I've trusted only DEET-containing products, but on longer camping trips I've worried about what the health effects could be from daily use of DEET without access to running water to wash it all away. The fact that lemon eucalyptus outperformed DEET is both surprising and encouraging.

Plus, my pets will be happy to finally have mosquito repellent that they can wear too

Why would lemon eucalyptus be safer for you then DEET? Because one smells less like a chemical?

I'm pretty sure the CDC suggests DEET for young children but not lemon eucalyptus so your intuition on which is safer is probably way off.

That said I'm going to use lemon eucalyptus because it smells better, regardless of any health issues..

Because lemon oil and eucalyptus oil are edible and known to be not harmful if ingested?

You try using DEET as ingredients in your food lol.

Eucalyptus is poisonous. Some may use it medicinally but if it's going to be ingested, it's recommended that it be very diluted.

I'm happy to see that the lemon eucalyptus product performed so well. For decades I've trusted only DEET-containing products, but on longer camping trips I've worried about what the health effects could be from daily use of DEET without access to running water to wash it all away. The fact that lemon eucalyptus outperformed DEET is both surprising and encouraging.

Plus, my pets will be happy to finally have mosquito repellent that they can wear too

Why would lemon eucalyptus be safer for you then DEET? Because one smells less like a chemical?

I'm pretty sure the CDC suggests DEET for young children but not lemon eucalyptus so your intuition on which is safer is probably way off.

That said I'm going to use lemon eucalyptus because it smells better, regardless of any health issues..

Because lemon oil and eucalyptus oil are edible and known to be not harmful if ingested?

You try using DEET as ingredients in your food lol.

Eucalyptus is poisonous. Some may use it medicinally but if it's going to be ingested, it's recommended that it be very diluted.

I'm happy to see that the lemon eucalyptus product performed so well. For decades I've trusted only DEET-containing products, but on longer camping trips I've worried about what the health effects could be from daily use of DEET without access to running water to wash it all away. The fact that lemon eucalyptus outperformed DEET is both surprising and encouraging.

Plus, my pets will be happy to finally have mosquito repellent that they can wear too

Why would lemon eucalyptus be safer for you then DEET? Because one smells less like a chemical?

I'm pretty sure the CDC suggests DEET for young children but not lemon eucalyptus so your intuition on which is safer is probably way off.

That said I'm going to use lemon eucalyptus because it smells better, regardless of any health issues..

Because lemon oil and eucalyptus oil are edible and known to be not harmful if ingested?

You try using DEET as ingredients in your food lol.

Eucalyptus is poisonous. Some may use it medicinally but if it's going to be ingested, it's recommended that it be very diluted.

Yes... only in large amounts?

That's why there's Eucalyptus oil in A LOT of uses in anti-septic and dental care? not only that, it's also used as flavoring and for scent component in soaps, perfumes, detergents and etc?

What's your point? Everything is poisonous in large amounts. At least long term effect of Eucalyptus oil is a known factor, unlike DEET.

I'm happy to see that the lemon eucalyptus product performed so well. For decades I've trusted only DEET-containing products, but on longer camping trips I've worried about what the health effects could be from daily use of DEET without access to running water to wash it all away. The fact that lemon eucalyptus outperformed DEET is both surprising and encouraging.

Plus, my pets will be happy to finally have mosquito repellent that they can wear too

Why would lemon eucalyptus be safer for you then DEET? Because one smells less like a chemical?

I'm pretty sure the CDC suggests DEET for young children but not lemon eucalyptus so your intuition on which is safer is probably way off.

That said I'm going to use lemon eucalyptus because it smells better, regardless of any health issues..

Because lemon oil and eucalyptus oil are edible and known to be not harmful if ingested?

You try using DEET as ingredients in your food lol.

Eucalyptus is poisonous. Some may use it medicinally but if it's going to be ingested, it's recommended that it be very diluted.

It's poison? Aw man! It smells so wonderful!

That's humans for you, always eating perversely. Take capsaicin - chilli plants fill their fruits with fire to ward off (the wrong) munching herbivores. Rather than being once-bitten-twice-shy humans find they like the aftermath, start competing to see who can eat the hottest.

Tangential anecdote. As a newly minted pharmacist in the 80's a client came in and after a thorough examination of the "wet and drys"* asked for "you-cal-a-PEET-us oil" I looked at my very experienced boss quizzically and he shrugged. "What are you using it for?" he asked. They were using it as a massage oil. He figured it out immediately.

* Wet and dries was the term used by pharmacists in the region for a section of oddball products, such as camphor sticks, anise oil, alum powder and such like.

I have to say from my (ok, 20 year old now) experience in South Carolina and Georgia, that citronella candles did work there, but that nothing seemed to work in western Alabama, other than smashing the little buggers flat.

Alabama was the only place where you could count the number of mosquitos that got trapped in the tent, from the number of tiny blood splats when we unrolled them the next night.

Those CO2 machines don't work worth a damn either, I had one for a few weeks it caught about 5 mosquitos in the bag, I exchanged it and the exchange got 4-5 more over the next couple weeks so I took it back. We had literal clouds of them in our yard at the time.

The highest DEET percentage you could get always worked best in Alaska

I'm happy to see that the lemon eucalyptus product performed so well. For decades I've trusted only DEET-containing products, but on longer camping trips I've worried about what the health effects could be from daily use of DEET without access to running water to wash it all away. The fact that lemon eucalyptus outperformed DEET is both surprising and encouraging.

Plus, my pets will be happy to finally have mosquito repellent that they can wear too

Why would lemon eucalyptus be safer for you then DEET? Because one smells less like a chemical?

I'm pretty sure the CDC suggests DEET for young children but not lemon eucalyptus so your intuition on which is safer is probably way off.

That said I'm going to use lemon eucalyptus because it smells better, regardless of any health issues..

Because lemon oil and eucalyptus oil are edible and known to be not harmful if ingested?

You try using DEET as ingredients in your food lol.

Eucalyptus is poisonous. Some may use it medicinally but if it's going to be ingested, it's recommended that it be very diluted.

I'm happy to see that the lemon eucalyptus product performed so well. For decades I've trusted only DEET-containing products, but on longer camping trips I've worried about what the health effects could be from daily use of DEET without access to running water to wash it all away. The fact that lemon eucalyptus outperformed DEET is both surprising and encouraging.

Plus, my pets will be happy to finally have mosquito repellent that they can wear too

Why would lemon eucalyptus be safer for you then DEET? Because one smells less like a chemical?

I'm pretty sure the CDC suggests DEET for young children but not lemon eucalyptus so your intuition on which is safer is probably way off.

That said I'm going to use lemon eucalyptus because it smells better, regardless of any health issues..

Because lemon oil and eucalyptus oil are edible and known to be not harmful if ingested?

You try using DEET as ingredients in your food lol.

Eucalyptus is poisonous. Some may use it medicinally but if it's going to be ingested, it's recommended that it be very diluted.

It's poison? Aw man! It smells so wonderful!

That's humans for you, always eating perversely. Take capsaicin - chilli plants fill their fruits with fire to ward off (the wrong) munching herbivores. Rather than being once-bitten-twice-shy humans find they like the aftermath, start competing to see who can eat the hottest.

Ahh, but they did attract the species that's good at agriculture in order to continue on their quest for world domination.

I'm happy to see that the lemon eucalyptus product performed so well. For decades I've trusted only DEET-containing products, but on longer camping trips I've worried about what the health effects could be from daily use of DEET without access to running water to wash it all away. The fact that lemon eucalyptus outperformed DEET is both surprising and encouraging.

Plus, my pets will be happy to finally have mosquito repellent that they can wear too

Why would lemon eucalyptus be safer for you then DEET? Because one smells less like a chemical?

I'm pretty sure the CDC suggests DEET for young children but not lemon eucalyptus so your intuition on which is safer is probably way off.

That said I'm going to use lemon eucalyptus because it smells better, regardless of any health issues..

Because lemon oil and eucalyptus oil are edible and known to be not harmful if ingested?

You try using DEET as ingredients in your food lol.

Eucalyptus is poisonous. Some may use it medicinally but if it's going to be ingested, it's recommended that it be very diluted.

It's poison? Aw man! It smells so wonderful!

That's humans for you, always eating perversely. Take capsaicin - chilli plants fill their fruits with fire to ward off (the wrong) munching herbivores. Rather than being once-bitten-twice-shy humans find they like the aftermath, start competing to see who can eat the hottest.

So why are there seeds inside hot chilis? If herbivores do not consume them and crap them out, what good are the seeds inside? Fruits have seeds and taste good so that beasts will munch them and spread the seeds around.Ahhhh, maybe that's where the resulting flaming diarrhea comes into play: the beasts that eat the fiery chili's get flaming squirts and thus projectile crap the seeds over a broader area. Plants are clever beings.

I'm happy to see that the lemon eucalyptus product performed so well. For decades I've trusted only DEET-containing products, but on longer camping trips I've worried about what the health effects could be from daily use of DEET without access to running water to wash it all away. The fact that lemon eucalyptus outperformed DEET is both surprising and encouraging.

Plus, my pets will be happy to finally have mosquito repellent that they can wear too

I don't think either one technically outperformed the other, both are within the percent error of each other which would make them statistically equal. They're both good.

It's the same with the sonic repeller vs the positive control. It doesn't mean the sonic repeller actually attracts mosquitoes instead, it likely just means it doesn't do anything statistically significant.

Picaridin needs to factor into these studies and discussions more often as an effective alternative to DEET.

I'd argue that a large part of the reason consumers turn to candles, bracelets and other ineffective repellents is because DEET is objectively nasty stuff. It smells bad, it feels bad, and it's all too effective as a solvent that damages stuff. Picaridin doesn't have any of these drawbacks.

20% Picaridin works for me (with nothing else), and also works for biting flies, which DEET doesn't. But that's unscientific. DEET still work the best for mosquitoes, as long as the fact that it melts plastic and nylon doesn't bother you.